Ocean temperature changes trigger
glacial melt A radar scientist tracking the rapid recession of
a West Antarctic glacier says that the glacier’s position on the continent
provides solid evidence that changes in ocean temperatures can trigger
the collapse of an ice sheet. Eric Rignot of the Jet Propulsion Laboratory
in Pasadena, Calif., published work in the July 24 Science tracking
the changing hinge line of the Pine Island Glacier over nearly four years.
Using radar interferometry data taken by the European Space Agency’s Earth
Remote Sensing Satellites (ERS-1 and 2), he found that the Pine Island
Glacier — an ice stream of the West Antarctic Ice Sheet — retreated inland
at about one kilometer a year between 1992 and 1996.
All glaciers experience basal melting, but Rignot
says the glacier’s fast retreat in this case is evidence of excess basal
melting. The excess melting, he found, caused the glacier to retreat 1.2
± 0.3 kilometers per year from its hinge line — the transition between
grounded ice and floating ice — at Pine Island Bay, which flows into the
Amundsen Sea on the southwest side of the continent. Overall, the glacier
thinned 3.5 ± 0.9 meters per year and retreated five kilometers
in 3.8 years.
Citing work published in 1996 by Stanley Jacobs,
Hartmut Hellmer, and Adrian Jenkins, Rignot says an influx of relatively
warm ocean waters from the southern Pacific apparently fuels high basal
melting of the Pine Island Glacier. Work by Jacobs and colleagues, as well
as by Terence Hughes of the University of Maine, suggests that basal melting
is sensitive to changes in ocean conditions and that the Pine Island Glacier,
located far south on the continent, is particularly sensitive to warmer
waters. Rignot says his inferred rate of ice thinning could be evidence
of excess basal melting caused by an increase of only 0.1º Celsius
in ocean temperature. The glaciers are tremendously sensitive to ocean
temperature, he says. “The large melt rates recorded near the hinge line
imply that Pine Island Glacier is even more sensitive to ice-ocean interactions
than was inferred from the 1994 survey [by Jacobs and colleagues] of ice-front
conditions.”

A history of collapse A team of researchers led by Reed P. Scherer of
Uppsala University in Sweden reported in the July 3 Science that, based
on glacial sediment samples recovered from beneath the West Antarctic Ice
Sheet, the massive ice sheet had collapsed in the late Pleistocene. At
least two ice shelves on the continent have retreated recently — the Wordie
Ice Shelf and the Larsen Ice Shelf on the Antarctic Peninsula at the northwest
end of Antarctica. The retreat of the Pine Island Glacier provides evidence
in the south of the melting of the ice sheet, Rignot says. Also, the Pine
Island Glacier sits in the main part of Antarctica. And unlike the Larsen
Ice Shelf, warm air temperature does not factor into the melting of the
Pine Island Glacier. “Something must be changing in the ocean,” he says.
“We’ve always thought about ice-sheet collapse through mechanical instabilities
or
drastic changes in precipitation or surface temperature. The case of
Pine Island Glacier raises the issue that changes in ocean waters — for
instance, changes in ocean currents could [alter] the temperature of the
ocean waters surrounding the glacier — are a far easier way to trigger
collapse of an ice sheet. That’s big news.”
Previous research shows the glacier is vulnerable
to climate change. Rignot attributes the glacier’s retreat to basal melting
by warm southern Pacific Ocean waters. If excess melting, brought on by
warmer temperatures in the southern Pacific Ocean, continues at the rate
he calculates, the West Antarctic Ice Sheet could eventually collapse.
Such a disintegration would raise sea level by several meters. “The retreat
of Pine Island Glacier is so large that it is hard to imagine a clearer
signal sent to us by the glacier for signaling [the ice sheet’s] imminent
collapse,” he says. — K.B.

Retreat of the redwoods It takes a lot to down a redwood. These hearty giants
of the forest have existed for millions of years. But the species hasn’t
always been confined, as it is today, to the forests of China and North
America. Once, redwoods dominated the landscape across North America, Europe,
and Asia. Then they were brought down — “conquered,” apparently, by the
pines they had peacefully co-existed with for 100 million years.
“It’s one of the most dramatic transitions in paleobotany,
and I wanted to know why it happened,” says Ben LePage, a geologist at
the University of Pennsylvania. A description of LePage’s research and
his explanation for the near-extinction of the redwoods were published
in early July in New Scientist. LePage tells New Scientist,
“The redwood design worked well for over 60 million years. What changed?”
LePage focused his studies on Axel Heiberg Island
in the Canadian Arctic. The island contains abundant evidence that 45 million
years ago, its hills were covered in a lush temperate woodland, quite different
from the arctic tundra of today. In some regions of the world, it’s easy
to ascribe environmental and ecological transformations to plate tectonics.
But here, the usual explanations for major climate change don’t apply so
neatly. LePage took advantage of Axel Heiberg Island’s geography and unique
environment to put together a picture of how the redwoods’ landscape was
transformed. It’s a story of how geologic and oceanographic changes, along
with some deep-rooted ecological associations, forced the mighty redwoods
into submission.

Geologic factorsAxel Heiberg Island has moved barely two degrees in tens of millions
of years, tectonically speaking. Oceanographically, however, there have
been enormous changes. Between 70 and 45 million years ago, ocean circulation
patterns of the proto-Gulf Stream kept temperatures in the north Atlantic
much higher than they are today. “Because the land masses had a different
shape then,” New Scientist reports, “ocean circulation pushed tropical
waters much further north.” But rifting in the sea floor between 55 and
33 million years ago created deep channels, linking the waters of the Arctic
and Atlantic Oceans, which
had been separated by the Greenland-Fennoscandian Ridge. These channels
“allowed cold, dense water from deep in the Arctic Ocean basin to drain
into the North Atlantic.” It took less than a million years for this transition
to occur. Ocean circulation patterns changed, and the climate rapidly cooled.
Says LePage, “For the forests on Axel Heiberg, the effects would have been
catastrophic. The entire ecosystem probably collapsed in a short space
of time.”
Other geological changes that would force the redwoods
to retreat were also occurring — the rise of the Rockies damaged the species
in North America, while the subsequent rise of the Himalayas adversely
affected the populations of redwoods in Asia. LePage explained to New
Scientist that the redwoods were effectively trapped, “unable to colonize
or survive at the new mountains’ higher altitudes. … Tracks of redwood
forest would simply have shriveled away.”
The Himalayan growth caused worldwide climate change
as well, cooling the globe over a period of 55 million years. This, too,
would have sped up the redwoods’ demise. LePage says that these explanations
for the contraction of the redwoods’ range are acceptable. But they don’t
answer all of his questions. Since the redwoods were able to co-exist with
the pine species for 100 million years — evident from the fossil plant
records on Axel Heiberg Island — LePage couldn’t understand why the pines
eventually replaced redwoods as the dominant trees in the north. “There
had to be some kind of Achilles heel that no one else had thought of,”
he says. He looked to the roots for the answer.

Deep-rooted associations For 12 years, LePage and his colleagues worked on
Axel Heiberg Island, excavating a remarkable deposit of leaves, roots,
and tree stumps — not fossilized, but mummified, incredibly preserved by
burial. The deposit has helped the scientists reconstruct the island’s
ecology, and has led LePage to the key to the redwoods’ fall. Pines and
redwoods, like most plants, have mycorrhizal roots. “That is,” LePage explains,
“their roots possess a symbiotic fungal association [that] is critical
when getting nutrients out of the soil.” But, as he realized, these two
species actually have different types of mycorrhizae.
The fungal strands of redwoods are associated with
root tissues, and are specially equipped to extract nutrients from the
soil in warm, rainy environments. But when the climate is dry or cold,
these endomycorrhizal fungi can’t do their job. Pines, on the other hand,
have mycorrhizae near the root’s surface. When the climate becomes cold
or dry, as happened on Axel Heiberg, “the pines come into their own, because
their ectomycorrhizae excel at obtaining nitrogen.” The redwoods couldn’t
break their bond with their fungi, so the pines started to take over until,
eventually, they dominated the northern forests. They had effectively pushed
the redwoods into confinement.
Axel Heiberg Island’s unique geology and the incredible
deposit of preserved flora provided important insight into how a species
can go into decline. Says Lisa Boucher, a paleobotanist at the University
of Nebraska, “It’s an elegant multidisciplinary synthesis. This work has
shown how key ‘choices’ in symbiotic relationships can strongly influence
a group’s evolutionary and ecological success.” — D.W.

Hot moons Two planetary moons are generating considerable
scientific speculation — and lots of heat. According to recent observations,
Neptune’s moon, Triton, is experiencing significant global warming, while
Io, one of Jupiter’s moons, now records the highest surface temperatures
of any planetary body in the solar system.

Triton heats up Researchers from the Lowell Observatory, the Massachusetts
Institute of Technology (MIT), and Williams College report in the June
25 issue of Nature that Triton, Neptune’s largest moon, has heated
up noticeably over the past 10 years. Recent observations from the Hubble
Space Telescope show that Triton’s atmosphere has doubled since the Voyager
space probe visited the moon in 1989. The increase in Triton’s atmospheric
pressure — strongly correlated to its surface temperature — implies a potential
increase from about 37 Kelvin (about -392ºF) to 39 Kelvin — the equivalent
of a jump of 22 degrees Fahrenheit on Earth.
“Since 1989, at least, Triton has been undergoing
a period of global warming. Percentage-wise, it’s a very large increase,”
says James L. Elliot, an astronomer at MIT. “For a northern summer on Earth,
it would be like the sun being directly overhead at noon, north of Lake
Superior.” The most likely theory is that Triton is approaching an extreme
southern summer, a season that occurs every few hundred years, Elliot explains.
During this season, more direct sunlight hits Triton’s
southern hemisphere, heating the polar ice caps. As a result, the nitrogen
ice vaporizes. That gas joins the atmosphere, forcing the increase in pressure.
Elliot and his colleagues were able to measure the pressure using one of
Hubble’s Fine Guidance Sensors. When Triton passed in front of “Tr180,”
a star in the constellation Sagittarius, the sensor measured the star’s
gradual decrease in brightness. The starlight became fainter as it traveled
through Triton’s thicker atmosphere.
Other explanations for Triton’s warmer weather are
also possible, the researchers say. Because the frost pattern on Triton’s
surface may have changed over the years, the moon may be absorbing more
of the sun’s warmth. Or, changes in the reflectivity of Triton’s ice may
have caused the moon to absorb more heat. Whatever the reasons, the temperature
change is significant; similar changes on Earth could drastically affect
its climate. Elliot and the other astronomers hope to gain insight into
Earth’s complicated environment by studying the changes on Triton. Although
Triton is a very different planet (at -390ºF, it’s a bit colder),
this factor actually helps the scientists. “With Triton, we can more easily
study environmental changes because of its simple, thin atmosphere,” Elliot
says. The atmosphere is gradually thickening, which could affect science
as much as it affects Triton. But, as Elliot says, “When you’re so cold,
global warming is a welcome trend.”

Io sizzles Neptune isn’t the only planet with a “hot moon.”
Volcanoes on Jupiter’s satellite, Io, are erupting at temperatures between
2,000 and 3,000ºF, higher than any surface temperatures ever recorded
on a planetary body. Planetary geologists at eight institutions, including
Brown University, the University of Arizona (UA), Lowell Observatory, and
the Jet Propulsion Laboratory, report in the July 3 issue of Science
that high-temperature hot spots are more common on Io than previously estimated.
Using Earth-based equipment and the Galileo
spacecraft, the researchers identified at least 30 locations at temperatures
greater than 700 Kelvin (800ºF). At least 12 different vents on Io
spew lava at temperatures greater than 2,200ºF, and one vent may be
as hot as 3,100ºF (2000 Kelvin). That’s three times hotter than the
hottest sunlit surface of Mercury and a drastic change in temperature from
the rest of Io’s surface, which, except for the hot spots, averages a chilly
-243ºF.
“The very hot lavas erupting on Io are hotter than
anything that has erupted on Earth for billions of years,” says Alfred
McEwen, director of UA’s Planetary Image Research Lab and lead author of
the Science paper. “They are the highest surface temperatures in
the solar system other than the sun itself.” The high temperatures are
more than double the highest temperatures recorded by the Voyager
spacecraft in 1979 and also exceed more recent measurements made by telescopes.
McEwen and his colleagues calculated the temperatures
using two instruments on Galileo that read the infrared signatures
of the vents. From the 1979 measurements, scientists had inferred that
Io’s volcanism was dominated by sulfur-rich lavas, but the new infrared
wavelength observations indicated that the lavas are ultramafic silicates,
specifically magnesium-rich pyroxenes. The lavas probably have a high melting
temperature, the scientists explain, and could be produced by large degrees
of partial melting. If this is the case, the mantle has undergone little
differentiation, retaining its primitive composition. This “suggests that
Io’s interior is similar to that of early Earth,” the authors write in
Science. Another explanation is that “volcanic activity has
strongly differentiated Io,” separating the mantle into layers of differing
density and composition. Extreme differentiation is expected, given Io’s
intense volcanism, says McEwen. “The evidence suggests we’re seeing heavy
magma erupt to the surface,” he adds. But it’s harder for dense material
to rise through a low-density crust. McEwen says that there could be some
process that mixes the crust back into Io’s interior, but the scientists
still aren’t sure how to explain what’s happening.
They do know that Io is heated because of its elliptical
orbit. Io passes close to Jupiter and then swings farther away; molded
by Jupiter’s massive gravitational forces at the different distances, Io
actually changes shape. This could cause Io to heat up. Co-author James
Head, professor of geological sciences at Brown University, explains, “It’s
almost as if Io is being kneaded by the tidal interactions between Jupiter
and the other moons.” — D.W.

More efforts to boost funding As the 105th Congress draws to a close, many in
the
scientific community wish the session would last a little longer. This
Congress has raised the visibility of science in a number of bills, but
none have passed and only a handful of days remain. The most recent bill,
S. 2217, the Federal Research Investment Act, passed the Senate Commerce
Committee in July. Even if it does not make it into law in this Congress,
it may serve as a template in the next.

Previous efforts Efforts to increase funding for research and development
(R&D) began back in January 1997 with the introduction of S. 124, the
National Research Investment Act of 1997, by Senator Phil Gramm (R-Texas).
Stating that “the United States simply does not spend enough on basic research,”
Gramm introduced a bill to authorize a doubling of nondefense R&D over
10 years. The bill provides specific increases for the National Institutes
of Health (NIH) and broadly calls for a doubling in funding for several
agencies, including the National Science Foundation, National Aeronautics
and Space Administration, National Oceanic and Atmospheric Administration,
Department of Energy (nondefense research), Department of Education, and
Environmental Protection Agency. As with all authorizing legislation, Gramm’s
bill would not guarantee an increase in funding; the actual appropriations
occur through a number of separate appropriations bills each year. But
the bill would put Congress on record as supporting increases in R&D.
The bill gained four sponsors and was referred to the Senate Committee
on Labor and Human Resources because of its provisions on NIH.
In October 1997, Sen. Joe Lieberman (D-Conn.), Sen.
Jeff Bingaman (D-N.M.), and Sen. Pete Domenici (R-N.M.) joined Gramm to
unveil a new, but similar bill: S. 1305, the National Research Investment
Act of 1998. The bill differs principally from S. 124 in its start date
(fiscal year 1999 instead of FY 1998) and bipartisan support rather than
only Republican co-sponsors. The bill was also referred to the Labor Committee,
where it, too, was ignored.

Federal Research Investment Act Building upon these earlier efforts, Senate Science,
Technology, and Space Subcommittee Chair Bill Frist (R-Tenn.), Ranking
Member John Rockefeller (D-W.Va.), and
S. 1305 co-sponsors worked to craft legislation that would fall under
the jurisdiction of Frist’s subcommittee. Along with Sen. Conrad Burns
(R-Mont.) and Sen. John Breaux (D-La.), the group unveiled S. 2217, the
Federal Research Investment Act, on June 25, 1998. The latest bill differs
from the earlier ones in several ways. It doubles R&D funding over
12 years, rather than 10. It also adds the Interior and Transportation
departments to the list of agencies whose research will be doubled. The
omission of the Department of the Interior, home of the U.S. Geological
Survey, in earlier bills had drawn concern from geoscientists, who advocated
for its inclusion in the later bill.
Perhaps the most significant distinction between
S. 2217 and previous bills is that it includes accountability provisions.
The
bill recommends that the White House Office of Science and Technology Policy
should commission the National Academy of Sciences (NAS) to develop methods
to evaluate federally funded R&D. The bill also instructs the administration
to provide — in conjunction with the budget request — a detailed summary
of the amount of R&D in the budget and a strategy for achieving the
doubling by 2010. These provisions are aimed at strength-ening the evaluation
of research and development. They follow the intent of the Govern-ment
Performance and Results Act, which instructs agencies to develop goals
and methods to achieve their goals, and to assess the success of their
programs. The NAS study is intended to improve the account-ability of agencies
conducting R&D because R&D outcomes are often difficult to predict
and do not follow standard performance measures. The bill calls for the
termination of programs that are determined to be below the acceptable
level of success for two fiscal years in a row, with certain exceptions.
Framers of S. 2217 slightly altered the wording
so that the bill could slip past the Labor and Human Resources Committee,
where similar bills had seen no action. Because it does not specify figures
for NIH, the bill was sent instead to the Commerce Committee, where Frist’s
subcommittee could act on it. The bill passed the subcommittee and later
passed the full Commerce Committee by a unanimous vote. The bill may pass
the full Senate in the final days of this Congress, but faces stiff competition
for attention as legislators wrap up the session and head home to blaze
the campaign trails for a fresh start in January.
—Kasey Shewey, AGI Government Affairs Program

Hot spots and low velocities The origin of hot spots is still up for debate,
but work published in the July 24 Science suggests that hot spots
originate in a 5- to 40-kilometer thick region at the base of the mantle.
This region, known as the ultra low velocity zone (ULVZ), stands out for
the unusual behavior demonstrated by compressional and shear waves passing
through it. The velocities of P waves in this region are depressed by as
much as 10 percent from the overlying mantle. Some scientists in the small
group of researchers studying the ULVZ say this velocity reduction could
indicate the presence of partial melt. These researchers have also theorized
that hot-spot volcanism, such as in Hawaii and Iceland, could result from
upwelling thermal plumes originating from the core-mantle boundary, where
ULVZs have been observed. Recent seismological studies suggest that the
core-mantle boundary is a structurally complex thermal boundary layer that
could play a large role in core and mantle dynamics. “The discovery of
patches of very low velocity, probably partially molten material, at the
base of the mantle is probably one of the most exciting discoveries in
the deep-Earth sciences in the past 10 years,” says seismologist Thorne
Lay, chair of the Earth Sciences Department at the University of California-Santa
Cruz.
Mineral physicist Quentin Williams and seismologist
Justin Revenaugh of UC-Santa Cruz and seismologist Ed Garnero of the University
of California-Berkeley determined that, sta-tistically, the correlation
be-tween the locations of known ultra low velocity zones and the locations
of known hot spots has a 1-percent chance of occurring randomly. “It basically
gives us a smoking gun for hot-spot genesis in the lower mantle,” Williams
says. “Correlation is not causation, but in our view it’s the next best
thing.” Williams says the work provides support for a long-standing idea
that hot spots originate in the lowermost mantle.
Williams and Garnero had also published work in
the Sept. 13, 1996, issue of Science stating that the velocity reductions
observed in the ULVZ most likely result from the presence of partial melt.
That idea gained more ground this year with work published in the Feb.
12 Nature by John Vidale of the University of Southern California
and Michael Hedlin of the University of California-San Diego. They observed
the scattering of seismic waves in a 60-kilometer-thick layer near the
core-mantle boundary beneath Tonga in the South Pacific Ocean. The scattering
they observed suggests the presence of partial melt and small-scale convection
at the core-mantle boundary, they write. (May Geotimes, p.10)
Williams and colleagues analyzed the known distribution
of hot spots and existing seismic studies showing ULVZs in six distinct
regions (beneath the northern and central Atlantic Ocean, beneath Africa,
south of Australia, and beneath the southwestern and northern Pacific Ocean).
Their first analysis was an algorithm determining the probability that
a given number of hot spots lying above the ULVZs could arise through random
processes. The second analysis calculated the probability that random rotations
of hot-spot distribution produced improved correlations with the structure
of the lowermost mantle relative to the actual hot-spot distribution. “The
reason we think the statistics are valid is we did the correlation in a
number of ways to eliminate biases in hot-spot distribution or ultra low
velocity zone sampling,” Williams says. “The correlation remains robust
even when we did everything we could to eliminate biases in the datasets.”
The team also conducted the analyses using tomographic models for the same
44 percent of the planet mapped for the ultra low velocity zones. “The
ULVZs produced a better correlation with both hot-spot distribution and
flux than either of the best correlated contours of the tomographic models,”
the researchers write. Williams adds that the correlations between hot
spots and mantle velocity anomalies decrease farther up the mantle. "You
really have to go to the deep part of the mantle for a correlation."
One obstacle the researchers faced was that only
a few ULVZs have been observed. Williams says previous work spanned about
33 percent of the core-mantle boundary for presence or absence of the low
velocity zones (much of that work has been conducted in just the past three
years by a relatively small number of researchers, including Garnero and
Revenaugh). The team conducted extra seismic studies to bring that percentage
to 44, focusing on the region below Asia.
The incomplete mapping of ULVZs still bothers Lay,
who published an article with Williams and Garnero in the April 2 Nature
that reviewed current knowledge of the core-mantle boundary. "Recent work
has shown that the very strong waveform anomalies that indicate the presence
of the ULVZ may be generated by quite localized structures," Lay says,
The heterogeneity of wave velocities could represent localized pockets
rather than a uniform layer, he and his colleagues wrote. "Thus, the correlation
[by WIlliams and colleagues] may be an artifact of the gross extrapolation
of area with ULVZ attributed to it. Further work and mapping of the structure
will be needed to assess this." Further mapping of the zone, he adds, could
negate the correlations made by the team.
At the same time, Lay agrees with Williams and other
ULVZ enthusiasts that an understanding of the ultra low velocity zone can
lead to an understanding of the dynamics of the mantle and its heat transport.
Williams feels confident that further research will support the idea that
hot spots and ULVZs are directly connected. As a mineral physicist, he
says, he wants to find out why partial melt in the zone would upwell to
the surface only at hot spots. He also wants to know if the melted zones
are stable over geologic time or are continuously regenerated, But like
other researchers, he mainly wants to understand what is causing the observed
ultra low velocity zone in seismic studies. "It's a very difficult problem
at this stage and it's a really important problem for understanding Earth's
dynamics. If we don't understand the ultra low velocity zone, we may not
understand mantle convection. — K.B.

Production: Domestic field production of petroleum
in April 1998 was estimated at 8,656 thousand barrels a day (crude
oil — 6,484; natural gas plant liquids — 1,859), according to the Energy
Information Administration. Domestic natural gas (dry) production in April
1998 was estimated at 1,566 billion cubic feet; domestic coal production
in April 1998 was estimated at 91,935 thousand short tons.

Oil and petroleum imports: U.S. imports of crude oil and petroleum
products in June 1998 averaged an estimated 10,725 thousand barrels a day,
a decrease of 0.1 percent from June 1997. The American Petroleum Institute,
Washington, D.C., reports imports met 52.76 percent of U.S. supply. In
June 1997, imports averaged 10,736 thousand barrels a day, and met 53.60
percent of U.S. supply. Supply in June 1998 was 1.5 percent higher than
in June 1997.

Earth Science Week is here This month marks the first annual Earth Science
Week, a celebration of the geosciences and their contributions to society.
Initiated by the American Geological Institute (AGI), Earth Science Week
takes place October 11-17. Seventeen state governors have proclaimed Earth
Science Week, and Oregon Sen. Ron Wyden entered the Earth Science Week
Proclamation (written by the Association of American State Geologists)
into the Congressional Record on July 15. AGI Program Manager Julie
Jackson says AGI has mailed more than 7,500 Earth Science Week information
packets in response to a wave of requests.
Throughout the country, schools, universities, state
geological surveys, museums, and geoscience societies are hosting special
events during the second week of October to highlight the work of earth
scientists and the contributions they make to our understanding of Earth.
The philosophy behind Earth Science Week is that the earth sciences are
fundamental to society and to our quality of life, Jackson says. The earth
sciences are crucial for addressing environmental and ecological issues,
and provide the basis for preparing for and mitigating natural hazards.
A few activities planned for the week include:

In Washington, D.C., AGI will start Earth Science Week at Taste of
D.C., an annual outdoor event that attracts more than 1 million people.

Also in Washington, the IRIS Consortium (Incorporated Research Institutions
for Seismology) hosts a celebration on Oct. 14 to honor seismologist Adam
Dziewonski and geophysicist Don Anderson. The scientists won the Crafoord
Prize from the Royal Swedish Academy of Science earlier this year.

Life in the ice A team of 10 scientists from five universities has
discovered microbial life deep in the ice of Antarctica. Using ice samples
from six lakes in the McMurdo Dry Valleys — Bonney, Hoare, Fryxell, Miers,
Vanda, and Vida — the researchers found that the ice meltwater in a layer
of sand below the surface supports “a viable microbial assemblage associated
with the sediment layer.” They report their findings in the June 26 issue
of Science.
Before this discovery, most investigators thought
that little biological activity could occur within the Antarctic ice. But
these microbe colonies exist on sunlight filtering through the ice that
activates and sustains life when the South Pole tilts toward the sun each
year. In fact, surprisingly diverse microorganisms abound throughout the
frozen lake water, supported by photosynthesis and atmospheric nitrogen
fixation.
“This discovery shows how life could exist on other
planets,” says Hans Paerl, professor of marine sciences at the University
of North Carolina at Chapel Hill. “Solar heating allows the water to melt
around soil particles that have blown over the ice and have been buried
in it. Microbes covering them can then spring to life within an hour under
certain conditions, even though they are still embedded deep in the ice."

What’s in the moon’s atmosphere? An intensive effort is underway to determine the
composition of the moon’s tenuous atmosphere. Although conventional wisdom
says the moon is devoid of atmosphere, and in layman’s terms this may be
close enough to the truth, the space just above the lunar surface is not
a total vacuum. Using the Suprathermal Ion Spectrometer (STICS) aboard
the WIND spacecraft, a team of scientists headed by Urs A. Mall
and Erhard Kirsch of the Max Planck Institute for Aeronomy in Germany have
identified the elements of several ions, including small amounts of oxygen,
silicon, and aluminum, in the lunar atmosphere. They will publish their
findings in an upcoming issue of Geophysical Research Letters.
Scientists believe the moon’s regolith, or surface
layer, is a significant source of atmospheric sodium. They want to learn
what other atoms the regolith releases and if those atoms form part of
the moon’s atmosphere.
The Apollo space program had identified helium and
argon atoms in the atmosphere, while Earth-based observations made in 1988
found sodium and potassium ions. Researchers hope to find more ions when
WIND
spends an extended period of time near the moon in November. The WIND
spacecraft was launched in 1994 as the first mission of the Global Geospace
Science initiative, part of the International Solar-Terrestrial Physics
(ISTP) program. The program aims to understand the physics of the Sun-Earth
relationship. The spacecraft passes the moon periodically.